25 waves pass through a point in 5s. If the distance between one crest and the adjacent trough is 0.05m , calculate

(a) the frequency

(b)the wavelength

(c)wave velocity

Frequency is equal to the numbers of wave passing through a point in one second. 

f = 25/5 = 5 Hz

Distance between one crest and the adjacent trough is 0.05 m

wavelength (λ) is equal to = 0.05 x 2 =  0.1 m

From the relation, 

V= f x λ = 5 x 0.1 = 0.5 m/s